From: Ira Weiny <[email protected]> Changes from V2[1]: Update this cover letter Update commit messages From Matthew Wilcox Put functions in highmem.h rather than pagemap.h Investigate 0-day build errors. AFAICT the patches were applied to the wrong tree and caused build errors.
There are many places in the kernel where kmap is used for a simple memory operation like memcpy, memset, or memmove and then the page is unmapped. This kmap/mem*/kunmap pattern is mixed between kmap and kmap_atomic uses. All of them could use kmap_atomic() which is faster. However, kmap_atomic() is being deprecated in favor of kmap_local_page(). Use kmap_local_page() in the existing page operations. Lift memcpy_[to|from]_page to highmem.h. Remove memzero_page() and use zero_user() instead. Add memcpy_page(), memmove_page(), and memset_page() to be used in future patches. Finally, add BUG_ON()s to check for any miss use of the API and prevent data corruption in the same way zero_user() does. This is V3 to get into 5.11 so that we can start to convert all the various subsystems in 5.12.[2] These are based on tip/core/mm. I'm sending to Andrew and Thomas but I'm expecting these to go through tip/core/mm via Thomas if that is ok with Andrew. [1] https://lore.kernel.org/lkml/[email protected]/ [2] https://lore.kernel.org/lkml/[email protected]/ Ira Weiny (2): mm/highmem: Remove deprecated kmap_atomic mm/highmem: Lift memcpy_[to|from]_page to core include/linux/highmem.h | 81 ++++++++++++++++++++++++++++++++++------- lib/iov_iter.c | 26 ++----------- 2 files changed, 70 insertions(+), 37 deletions(-) -- 2.28.0.rc0.12.gb6a658bd00c9
